Solid-state imaging element, method for manufacturing the same, and electronic apparatus

ABSTRACT

The present technology relates to a solid-state imaging element configured so that pixels can be more reliably separated, a method for manufacturing the solid-state imaging element, and an electronic apparatus. The solid-state imaging element includes a photoelectric converter, a first separator, and a second separator. The photoelectric converter is configured to perform photoelectric conversion of incident light. The first separator configured to separate the photoelectric converter is formed in a first trench formed from a first surface side. The second separator configured to separate the photoelectric converter is formed in a second trench formed from a second surface side facing a first surface. The present technology is applicable to an individual imaging element mounted on, e.g., a camera and configured to acquire an image of an object.

TECHNICAL FIELD

The present technology relates to a solid-state imaging element, amethod for manufacturing the solid-state imaging element, and anelectronic apparatus. Specifically, the present technology relates to asolid-state imaging element configured so that pixels can be morereliably separated, the method for manufacturing the solid-state imagingelement, and the electronic apparatus.

BACKGROUND ART

In a solid-state imaging element, a plurality of pixels are arranged.Thus, for preventing color mixture, photoelectric converters formingadjacent pixels need to be separated, and various proposals have beenmade for such a demand.

For example, Patent Document 1 proposes that a separation structure isformed before formation of photodiodes and a P-type impurity is diffusedon a trench surface by a solid-phase diffusion technique to form aP-type diffusion layer.

Moreover, Patent Document 2 proposes that a trench is formed from alight receiving surface side and pixels are separated together with aP-type impurity between photodiodes.

Further, Patent Document 3 proposes that a trench is formed at theperiphery of a photodiode and a PN joint is formed at a side wall of thetrench. In this manner, an electric field of a peripheral portion isintensified, and a saturated charge amount Qs is increased. A P-typeimpurity layer is formed by ion implantation or solid-phase diffusion,and an N-type impurity layer is formed by ion implantation.

CITATION LIST Patent Document Patent Document 1: Japanese Patent No.4987917 Patent Document 2: Japanese Patent Application Laid-Open No.2013-157422 Patent Document 3: Japanese Patent Application Laid-Open No.2015-153772 SUMMARY OF THE INVENTION Problems to be Solved by theInvention

However, in the proposal of Patent Document 1, there is restriction on apixel transistor area in a fine pixel, and offset needs to be made in adepth direction. For these reasons, sufficient separation by a trenchstructure is difficult.

In the proposal of Patent Document 2, high-heat treatment cannot be usedbecause a trench structure is formed after formation of the photodiodes.For this reason, it is difficult to perform additional impurityprocessing, and a P-type diffusion layer needs to be formed on a trenchsurface in advance.

In the proposal of Patent Document 3, the N-type impurity is formed byion implantation. For this reason, the impurity expands in a transversedirection, and therefore, a steep PN joint cannot be formed. Thus, thereare limitations on electric field intensification and improvement of thesaturated charge amount Qs.

As a result, it is difficult to sufficiently separate pixels by theseproposals.

The present technology has been made in view of these situations, and isintended to more reliably separate pixels.

Solutions to Problems

One aspect of the present technology is a solid-state imaging elementincluding: a photoelectric converter configured to perform photoelectricconversion of incident light; a first separator configured to separatethe photoelectric converter and formed in a first trench formed from afirst surface side; and a second separator configured to separate thephotoelectric converter and formed in a second trench formed from asecond surface side facing a first surface.

In the first trench, a first impurity layer formed of an N-type impurityand a second impurity layer formed of a P-type impurity may be formed bysolid-phase diffusion.

The first separator and the second separator may be arranged next toeach other in a direction parallel to an optical axis of a lens throughwhich light enters the photoelectric converter.

The photoelectric converter may include photoelectric converters in twotiers, the photoelectric converter on the first surface side beingseparated by the first separator and the photoelectric converter on thesecond surface side being separated by the second separator.

A periphery of a block including 2×2 photoelectric converters may beseparated by the first separator.

The first separator and the second separator may be arranged next toeach other in a direction perpendicular to an optical axis of a lensthrough which light enters the photoelectric converter.

In the first trench, a first impurity layer formed of an N-typeimpurity, a second impurity layer formed of a P-type impurity, and athermally-oxidized film may be formed.

A wiring layer may be disposed on the first surface side of asemiconductor layer having the photoelectric converter, the firstseparator, and the second separator, and an optical layer may bedisposed on the second surface side.

One aspect of the present technology is a method for manufacturing asolid-state imaging element, including: a step of forming a first trenchfrom a first surface side; a step of forming, in the first trench, afirst separator for separating a photoelectric converter; a step offorming a second trench from a second surface side facing a firstsurface; and a step of forming, in the second trench, a second separatorfor separating the photoelectric converter.

One aspect of the present technology is an electronic apparatusincluding: a solid-state imaging element configured to acquire an imageof an object; and a signal processor configured to process an imagesignal output from the solid-state imaging element, in which thesolid-state imaging element includes a photoelectric converterconfigured to perform photoelectric conversion of incident light, afirst separator configured to separate the photoelectric converter andformed in a first trench formed from a first surface side, and a secondseparator configured to separate the photoelectric converter and formedin a second trench formed from a second surface side facing a firstsurface.

One aspect of the present technology is a solid-state imaging elementincluding: a photoelectric converter configured to perform photoelectricconversion of incident light; and a separator configured to separate thephotoelectric converter, in which the separator includes N-type andP-type impurity layers formed in a trench for separating thephotoelectric converter, and a thermally-oxidized film formed on theimpurity layers.

The impurity layers may be formed by solid-phase diffusion.

The N-type impurity layer may be formed only on a transfer gate side inthe trench, and may not be formed on an opposite side of the transfergate.

An embedded film to which a predetermined voltage is to be applied maybe embedded in the trench.

A fixed charge film with a negative fixed charge may be formed on thethermally-oxidized film.

The separator may be formed surrounding a periphery of a pixel.

The trench may be formed from a first surface side of a semiconductorlayer having the photoelectric converter and the separator, a wiringlayer being disposed on the first surface side, and an optical layer maybe disposed on a second surface side facing a first surface.

The impurity layers may be formed by tilt ion implantation, plasmadoping, epitaxial growth, or vapor-phase diffusion.

In one aspect of the present technology, the photoelectric converter isconfigured to perform photoelectric conversion of incident light throughthe lens, the wiring layer is configured such that a line fortransmitting/receiving a signal to/from the photoelectric converter isdisposed on the opposite side of the lens, and the separators areconfigured such that adjacent photoelectric converters are separated bythe first separator in the first trench formed from the side on whichthe wiring layer is disposed and the second separator in the secondtrench formed from the side on which the lens is disposed.

Effects of the Invention

As described above, according to one aspect of the present technology,the pixels can be more reliably separated. Note that the advantageouseffects described in the present specification are mere examples, andare not limited. Moreover, additional advantageous effects may beprovided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view of a configuration of a solid-state imaging element ofa first embodiment of the present technology.

FIG. 2 is a view of the configuration of the solid-state imaging elementof the first embodiment of the present technology.

FIG. 3 is a flowchart for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology.

FIG. 4 is a view for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology.

FIG. 5 is a view for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology.

FIG. 6 is a view for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology.

FIG. 7 is a view for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology.

FIG. 8 is a view for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology.

FIG. 9 is a view for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology.

FIG. 10 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 11 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 12 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 13 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 14 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 15 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 16 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 17 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 18 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 19 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 20 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 21 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 22 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 23 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 24 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 25 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology.

FIG. 26 is a view of a configuration of a solid-state imaging element ofa second embodiment of the present technology.

FIG. 27 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 28 is a graph for describing characteristics of the solid-stateimaging element of the second embodiment of the present technology.

FIG. 29 is a flowchart for describing the method for manufacturing thesolid-state imaging element of the second embodiment of the presenttechnology.

FIG. 30 is a view for describing the method for manufacturing thesolid-state imaging element of the second embodiment of the presenttechnology.

FIG. 31 is a view for describing the method for manufacturing thesolid-state imaging element of the second embodiment of the presenttechnology.

FIG. 32 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 33 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 34 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 35 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 36 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 37 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 38 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 39 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology.

FIG. 40 is a flowchart for describing the method for manufacturing thesolid-state imaging element of the second embodiment of the presenttechnology.

FIG. 41 is a view for describing the method for manufacturing thesolid-state imaging element of the second embodiment of the presenttechnology.

FIG. 42 is a diagram for describing a configuration of an electronicapparatus of a third embodiment of the present technology.

MODE FOR CARRYING OUT THE INVENTION

Modes for carrying out the present technology will be described below.Note that description will be made in the following order.

1. First Embodiment: Combination of FDTI and RDTI (FIG. 1 to FIG. 25)

(1) Outline Configuration Example of Solid-State Imaging Element (FIG.1)

(2) Configuration of Combination of FDTI and RDTI (FIG. 2, FIG. 10, FIG.11)

(3) Method for Manufacturing Solid-State Imaging Element (FIG. 3 to FIG.9)

(4) Configuration 1 of Another Combination of FDTI and RDTI (FIG. 12,FIG. 13)

(5) Configuration 2 of Still Another Combination of FDTI and RDTI (FIG.14, FIG. 15)

(6) Configuration 3 of Still Another Combination of FDTI and RDTI (FIG.16, FIG. 17)

(7) Configuration 4 of Still Another Combination of FDTI and RDTI (FIG.18, FIG. 19)

(8) Configuration 5 of Still Another Combination of FDTI and RDTI (FIG.20, FIG. 21)

(9) Configuration 6 of Still Another Combination of FDTI and RDTI (FIG.22, FIG. 23)

(10) Configuration 7 of Still Another Combination of FDTI and RDTI (FIG.24, FIG. 25)

2. Second Embodiment: FDTI (FIG. 26 to FIG. 41)

(1) Configuration of FDTI (FIG. 26, FIG. 27, FIG. 28)

(2) Method for Manufacturing FDTI (FIG. 29, FIG. 30, FIG. 31)

(3) Another Configuration 1 of FDTI (FIG. 32)

(4) Still Another Configuration 2 of FDTI (FIG. 33)

(5) Still Another Configuration 3 of FDTI (FIG. 34)

(6) Still Another Configuration 4 of FDTI (FIG. 35)

(7) Still Another Configuration 5 of FDTI (FIG. 36)

(8) Still Another Configuration 6 of FDTI (FIG. 37)

(9) Still Another Configuration 7 of FDTI (FIG. 38)

(10) Still Another Configuration 8 of FDTI (FIG. 39)

(11) Another Method for Manufacturing FDTI (FIG. 40, FIG. 41)

3. Third Embodiment: (Electronic apparatus Using Solid-State ImagingElement) (FIG. 42)

4. Other

FIRST EMBODIMENT

(Combination of FDTI and RDTI)

(1) Outline Configuration Example of Solid-State Imaging Element

FIG. 1 is a view of a configuration of a solid-state imaging element ofa first embodiment of the present technology. FIG. 1 illustrates anoutline configuration of a metal oxide semiconductor (MOS) typesolid-state imaging element as an example of a solid-state imagingelement provided with the solid-state imaging element of the presenttechnology.

The solid-state imaging element 1 illustrated in this figure has a pixelregion 4 where a plurality of pixels 3 each including a photoelectricconversion region are two-dimensionally arranged on one surface of asupport substrate 2. Each pixel 3 disposed in the pixel region 4 isprovided with a pixel circuit including, for example, the photoelectricconversion region, a floating diffusion, a reading gate, multiple othertransistors (so-called MOS transistors), and a capacitive element. Notethat the plurality of pixels 3 may sometimes share part of the pixelcircuit.

A peripheral portion of the pixel region 4 described above is providedwith peripheral circuits such as a vertical drive circuit 5, columnsignal processing circuits 6, a horizontal drive circuit 7, and a systemcontrol circuit 8.

The vertical drive circuit 5 includes, for example, a shift resistor.The vertical drive circuit 5 is configured to select a pixel drive line9 to supply the selected pixel drive line 9 with a pulse for driving thepixels 3, thereby driving, in units of rows, the pixels 3 arranged inthe pixel region 4. That is, the vertical drive circuit 5 selectivelyand sequentially scans each pixel in the vertical direction in units ofrows, each pixel being disposed in the pixel region 4. Then, a pixelsignal based on a signal charge generated according to a received lightamount in each pixel 3 is supplied to the column signal processingcircuit 6 via a vertical drive line 10 disposed perpendicular to thepixel drive line 9.

The column signal processing circuit 6 is disposed for each column ofthe pixels, for example. The column signal processing circuit 6 isconfigured to perform, for each pixel column, signal processing ofsignals output from a single line of pixels 3, such as noise removal.That is, the column signal processing circuit 6 performs the signalprocessing for removing pixel-specific fixed pattern noise, such ascorrelated double sampling (CDS), signal amplification, oranalog/digital conversion (AD).

The horizontal drive circuit 7 includes, for example, a shift resistor.The horizontal drive circuit 7 is configured to sequentially output ahorizontal scanning pulse to sequentially select each of the columnsignal processing circuits 6, thereby causing each of the column signalprocessing circuits 6 to output the pixel signals.

The system control circuit 8 is configured to receive an input clock anddata for commanding an operation mode etc. and to output data such asinternal information of the solid-state imaging element 1. That is, inthe system control circuit 8, a clock signal and a control signal as areference of operation of the vertical drive circuit 5, the columnsignal processing circuits 6, the horizontal drive circuit 7, etc. aregenerated on the basis of a vertical synchronization signal, ahorizontal synchronization signal, and a master clock. Then, thesesignals are input to the vertical drive circuit 5, the column signalprocessing circuits 6, the horizontal drive circuit 7, etc.

Each peripheral circuit and the pixel circuit provided in the pixelregion 4 as described above form a drive circuit configured to driveeach pixel. Note that the peripheral circuits may be arranged atpositions stacked on the pixel region 4.

(2) Configuration of Combination of FDTI and RDTI

FIG. 2 is a view of the configuration of the solid-state imaging elementof the first embodiment of the present technology. A configuration of acombination of a front deep trench isolation (FDTI) and a rear deeptrench isolation (RDTI) of the solid-state imaging element 1 will bemainly described below with reference to FIG. 2.

FIG. 2 illustrates a configuration of a solid-state imaging element 51as part of the solid-state imaging element 1 of FIG. 1. B and C of FIG.2 respectively illustrate configurations of back and front surfaces ofthe solid-state imaging element 51, and A of FIG. 2 illustrates aconfiguration of a cross section of the solid-state imaging element 51along an A-A′ line of C of FIG. 2.

A of FIG. 2 illustrates a state in which an optical layer 164 having acolor filter 66 and lenses 67 is disposed on an upper side (a backsurface side) of a semiconductor layer 163 and nothing is disposed on alower side (a front surface side). However, it is actually configuredsuch that a wiring layer 162 is disposed on a first surface side (thefront surface side) of the semiconductor layer 163 and the optical layer164 is disposed on a second surface side (the back surface side) facinga first surface as illustrated in B of FIG. 7 described later. That is,the solid-state imaging element 1 is a solid-state imaging elementrepresented by a backside illumination type complementary metal oxidesemiconductor (CMOS) image sensor.

The semiconductor layer 163 is provided with photodiodes 65 asphotoelectric converters. The lenses 67 are arranged correspondingrespectively to the photodiodes 65. The photodiode 65 is configured toperform photoelectric conversion of light input through the opticallayer 164, i.e., the lens 67 and the color filter 66, and correspondingto a color of the color filter 66. In the semiconductor layer 163, eachphotodiode 65 is separated by a FDTI 61 and a RDTI 62 as separators.

The FDTI 61 as a first separator is a separator formed on the basis of atrench (a trench 111 of B of FIG. 4 described later) formed from thefront surface side of the solid-state imaging element 51. That is, theFDTI 61 is a separator formed on the basis of a trench formed from thefront surface (a surface on the lower side as viewed in A of FIG. 2,i.e., a surface opposite to a surface on which the lenses 67 arearranged, i.e., a side on which the later-described wiring layer 162illustrated in B of FIG. 7 is disposed) of the solid-state imagingelement 51. The trench forming the FDTI 61 has, on a surface thereof, animpurity layer 63 formed of an N-type impurity, and an impurity layer 64formed of a P-type impurity.

Conversely, the RDTI 62 as a second separator is a separator formed onthe basis of a trench (a trench 171 of D of FIG. 6 described later)formed from the back surface (a surface on the upper side as viewed in Aof FIG. 2, i.e., the surface on the side on which the lenses 67 arearranged) of the solid-state imaging element 51.

As illustrated in A of FIG. 2, the FDTI 61 and the RDTI 62 face, in thepresent embodiment, the same side surface of the photodiode 65, and arearranged next to each other in a direction (i.e., a longitudinaldirection) parallel to the optical axis of the lens 67. Moreover, theFDTI 61 and the RDTI 62 directly contact each other, but both may beoffset (i.e., apart) from each other. In a case where the FDTI 61 andthe RDTI 62 are offset from each other, a P-type impurity is insertedinto such an offset portion.

Moreover, in the present embodiment, four side surfaces on the backsurface side (a side of the photodiode 65 close to the lens 67) areseparated by the RDTI 62 as illustrated in B of FIG. 2. On the otherhand, three of the four side surfaces are, on the front surface side (aside opposite to the lens 67), separated by the FDTI 61 as illustratedin C of FIG. 2. That is, adjacent 2×2 photodiodes 65 form a singleblock, and surrounding side surfaces thereof are separated by the FDTI61.

A floating diffusion (FD) 71 is disposed at the center of each block,and a transfer gate (TG) 72 is disposed close to the FD 71 at eachphotodiode 65. Moreover, a pixel transistor 73 is disposed on the lowerside of each block as viewed in C of FIG. 2. The pixel transistor 73 andthe photodiodes 65 are separated by the FDTI 61.

Of the 2×2 photodiodes 65 in each block, adjacent photodiodes 65 in anupper-to-lower direction in C of FIG. 2 are separated by a P-typeimpurity layer 81 such as boron. Moreover, of the 2×2 photodiodes 65 ineach block, part of adjacent photodiodes 65 in a right-to-left directionin C of FIG. 2 is separated by the FDTI 61, and the remaining part ofsuch photodiodes 65 is separated by the impurity layer 81.

(3) Method for Manufacturing Solid-State Imaging Element

Next, the method for manufacturing the solid-state imaging element 51will be described with reference to FIG. 3 to FIG. 7. FIG. 3 is aflowchart for describing the method for manufacturing the solid-stateimaging element of the first embodiment of the present technology, andFIG. 4 to FIG. 7 are views for describing the method for manufacturingthe solid-state imaging element of the first embodiment of the presenttechnology.

First, the processing of preparing a substrate is executed at a stepS11. A of FIG. 4 illustrates the prepared silicon (Si) substrate 101,for example. Ata step S12, trench processing for a FDTI 61 is executed.That is, as illustrated in B of FIG. 4, trenches 111 are, by lithographyand etching, formed at the substrate 101 prepared at the step S11. In Bof FIG. 4, a front surface side (i.e., a side on which a wiring layer162 is to be disposed) of a semiconductor layer 163 is in an upwarddirection. That is, the trenches 111 are formed from the front surfaceside (i.e., a first surface side on which the wiring layer 162 is to bedisposed) of the semiconductor layer 163 (these trenches are for formingthe FDTI 61 of B of FIG. 7 described later).

At a step S13, the processing of forming, on a surface of each trench111, a film doped with an N-type impurity is executed. For example, asillustrated in C of FIG. 4, a film 121 doped with phosphorus (P) isformed in each trench 111 by, e.g., chemical vapor deposition (CVD).

At a step S14, the processing of performing solid-phase diffusion of theN-type impurity is executed. That is, solid-phase diffusion is performedin such a manner that the phosphorus film 121 formed by the processingof the step S13 is thermally processed. Because it is still beforeformation of photodiodes 65, there is a low probability that the heattreatment poses an obstacle. Thus, as illustrated in D of FIG. 4, anN-type impurity layer 63 is formed in the substrate 101 at the peripheryof each trench 111.

At a step S15, the processing of removing the film 121 doped with theN-type impurity is executed. That is, the film 121 formed in each trench111 at the step S13 is removed. This brings a state in which the N-typeimpurity layer 63 is formed in the substrate 101 at the periphery ofeach trench 111 as illustrated in A of FIG. 5.

At a step S16, the processing of forming, on the surface of each trench111, a film doped with a P-type impurity is executed. For example, asillustrated in B of FIG. 5, a film 131 of a P-type impurity such asboron (B) is formed in each trench 111 by, e.g., CVD.

At a step S17, the processing of performing solid-phase diffusion of theP-type impurity is executed. That is, solid-phase diffusion of theP-type impurity is performed in such a manner that heat treatment isperformed for the P-type impurity film 131 formed at the step S16.Because it is still before formation of the photodiodes 65, there is alow probability that the heat treatment poses an obstacle. Thus, asillustrated in C of FIG. 5, a P-type impurity layer 64 is formed in thesubstrate 101 (i.e., in a region where the impurity layer 63 is formed)at the periphery of each trench 111, for example.

At a step S18, the processing of removing the film 131 doped with theP-type impurity is executed. That is, as illustrated in D of FIG. 5, thefilm 131 formed for solid-phase diffusion in each trench 111 at the stepS16 is removed, leading to a state in which the N-type impurity layer 63and the P-type impurity layer 64 are formed in the substrate 101 at theperiphery of each trench 111.

The N-type impurity layer 63 and the P-type impurity layer 64 having aconcentration level similar to 1SR are formed, and therefore, an intenseelectric field portion is produced at a side wall of the FDTI 61.Consequently, both of separation between pixels and improvement of asaturated charge amount Qs can be realized.

At a step S19, the processing of embedding an insulator in each trench111 for the FDTI is executed. For example, as illustrated in A of FIG.6, an embedded film 141 made of an insulator such as SiO₂ is embedded ineach trench 111. In this manner, the FDTI 61 is formed.

At a step S20, the processing of forming the photodiodes 65 is executed.That is, as illustrated in B of FIG. 6, the photodiodes 65 are formed byion implantation of an N-type impurity. In this manner, thesemiconductor layer 163 is formed. Further, agate, peripheraltransistors, and a wiring layer are formed.

Moreover, for pinning of a RDTI 62, a P-type impurity is implanted intoa region 151 between adjacent ones of the photodiodes 65. Note that suchprocessing can be omitted in a case where a fixed charge film is usedfor a surface of the RDTI 62. The fixed charge film will be describedlater.

At a step S21, the processing of bonding a support base is executed.Thus, a configuration is realized, in which the wiring layer 162 isdisposed on the support base 161 and the semiconductor layer 163 isfurther disposed on the wiring layer 162 as illustrated in C of FIG. 6.In the wiring layer 162, a line for transmitting/receiving a signalto/from the photodiode 65 is disposed. Then, alight reception side(i.e., an upper surface of the semiconductor layer 163 of C of FIG. 6)is polished.

At a step S22, trench processing for the RDTI 62 is executed. That is,as illustrated in D of FIG. 6, a trench 171 for the RDTI 62 is formed inthe region 151 between adjacent ones of the photodiodes 65. In D of FIG.6, a back surface side (i.e., a second surface side on which an opticallayer 164 is to be disposed) of the semiconductor layer 163 is in anupward direction. That is, the trenches 171 are formed from the backsurface side (i.e., the side on which the optical layer 164 is to bedisposed) of the semiconductor layer 163 (these tranches are for formingthe RDTI 62 of B of FIG. 7 described later).

At a step S23, the processing of embedding an embedded film in eachtrench 171 for the RDTI 62 is executed. That is, as illustrated in A ofFIG. 7, an embedded film 181 made of an insulator such as SiO₂ isembedded into the region 151 between adjacent ones of the photodiodes65. In this manner, the RDTI 62 is formed on the FDTI 61 (on the lightreception side).

At a step S24, the processing of forming a color filter 66 and lenses 67is executed. That is, as illustrated in B of FIG. 7, the optical layer164 including the color filter 66 and the lenses 67 is formed on thesemiconductor layer 163. That is, the lenses 67 are arranged on the backsurface side, and the wiring layer 162 is disposed on the front surfaceside (a side opposite to the lenses 67). In this manner, the solid-statesemiconductor element 51 is manufactured.

Note that manufacturing methods as illustrated in FIG. 8 and FIG. 9 canbe employed. FIG. 8 is a view for describing the method formanufacturing the solid-state imaging element of the first embodiment ofthe present technology. The depth of the FDTI 61 is 0.5 to 2 μm which isdeeper than a shallow trench isolation (STI) with around 0.3 μm. Inaddition to the FDTI 61 and the RDTI 62, the STI can be combined. Inthis case, the trenches 111 are formed after a STI 191 has been formedin advance, and then, solid-phase diffusion of the N-type impurity layer63 is further performed, as illustrated in A of FIG. 8. Then, asillustrated in B of FIG. 8, solid-phase diffusion of the P-type impuritylayer 64 is further performed. Thereafter, the processing of implantingthe photodiodes 65 and formation of the peripheral transistors arefurther executed.

FIG. 9 is a view for describing the method for manufacturing thesolid-state imaging element of the first embodiment of the presenttechnology. In this example, lightly doped drains (LDDs), sidewalls,sources, drains, etc. of a pixel transistor and a logic transistor areformed after the processing of implanting the photodiodes 65 and theprocessing of forming a gate 201 have been performed. Then, asillustrated in A of FIG. 9, the trenches 111 are formed, and the N-typeimpurity layer 63 is formed by solid-phase diffusion. Further, asillustrated in B of FIG. 9, the P-type impurity layer 64 is formed bysolid-phase diffusion.

Moreover, in the above-described example, the FDTI 61 and the RDTI 62are formed to directly contact each other, but can be offset from eachother in the longitudinal direction or a transverse direction. FIG. 10illustrates an example of this case. FIG. 10 is a view of theconfiguration of the solid-state imaging element of the first embodimentof the present technology. In the example of FIG. 10, the FDTI 61 isslightly offset (i.e., shifted) inward from the RDTI 62.

The solid-state imaging element 51 illustrated in FIG. 2 can have abacksurface configuration as illustrated in FIG. 11 instead of theconfiguration illustrated in B of FIG. 2. FIG. 11 is a view of theconfiguration of the solid-state imaging element of the first embodimentof the present technology. As clearly seen from comparison between FIG.11 and B of FIG. 2, a configuration example of FIG. 11 is made such thatintersection portions of the RDTI 62 contacting four side surfaces ofeach photodiode 65 are separated by the P-type impurity layer 81. Otherconfigurations are similar to those in the case illustrated in B of FIG.2.

(4) Configuration 1 of Another Combination of FDTI and RDTI

A configuration of another combination of the FDTI 61 and the RDTI 62will be described below. FIG. 12 is a view of the configuration of thesolid-state imaging element of the first embodiment of the presenttechnology. B and C of FIG. 12 respectively illustrate theconfigurations of the back and front surfaces of the solid-state imagingelement 51, and A of FIG. 12 illustrates a configuration of a crosssection of the solid-state imaging element 51 along an A-A′ line of C ofFIG. 12.

In a configuration example of FIG. 12, four side surfaces of eachphotodiode 65 on a back surface side are separated by a RDTI 62 asillustrated in B of FIG. 12. On a front surface side, 2×2 photodiodes 65on the front surface side (the lower side as viewed in A of FIG. 12)form, on the other hand, a single block, and the periphery thereof isseparated by a FDTI 61 as illustrated in C of FIG. 12.

Of the 2×2 photodiodes 65 of each block, adjacent photodiodes 65 in aright-to-left direction in C of FIG. 12 are separated by a P-typeimpurity layer 81. Moreover, of the 2×2 photodiodes 65 of each block,right and left end portions of adjacent photodiodes 65 in anupper-to-lower direction in C of FIG. 12 are separated by the FDTI 61,and the remaining center portions of these photodiodes 65 are separatedby the impurity layer 81. Of four side surfaces on the front surfaceside, three side surfaces are separated by the FDTI 61.

Thus, as illustrated in A of FIG. 12, the configuration of the crosssection along the A-A′ line of C of FIG. 12 is, on the front surfaceside (the lower side as viewed in A of FIG. 12), made such that the FDTI61 and the impurity layer 81 alternately separate the photodiodes 65arranged in the right-to-left direction. On the back surface side (theupper side as viewed in A of FIG. 12), the photodiodes 65 are separatedby the RDTI 62. That is, one side surface of each photodiode 65 isseparated by the FDTI 61 and the RDTI 62, and another side surface ofsuch a photodiode 65 is separated by the RDTI 62 and the impurity layer81. Other configurations are similar to those in the case of FIG. 2.

FIG. 13 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. Thesolid-state imaging element 51 illustrated in FIG. 12 can have a backsurface configuration as illustrated in FIG. 13 instead of theconfiguration illustrated in B of FIG. 12. As clearly seen fromcomparison between FIG. 13 and B of FIG. 12, a configuration example ofFIG. 13 is made such that intersection portions of the RDTI 62contacting four side surfaces of each photodiode 65 are separated by theP-type impurity layer 81. Other configurations are similar to those inthe case illustrated in B of FIG. 12.

(5) Configuration 2 of Still Another Combination of FDTI and RDTI

FIG. 14 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. B and C ofFIG. 14 respectively illustrate the configurations of the back and frontsurfaces of the solid-state imaging element 51, and A of FIG. 14illustrates a configuration of a cross section of the solid-stateimaging element 51 along an A-A′ line of C of FIG. 14.

FIG. 14 illustrates a dual pixel configuration example. In thisconfiguration example, photodiodes 65 in the same color selected fromeach color of red (R), green (G), and blue (B) are, two by two, arrangednext to each other as illustrated in B of FIG. 12. In the example of Bof FIG. 14, two upper left photodiodes 65 and two lower rightphotodiodes 65 are in the color of G, two upper right photodiodes 65 arein the color of B, and two lower left photodiodes 65 are in the color ofR.

Moreover, on a back surface side, two photodiodes 65 in the same colorforma block, and adjacent blocks are separated by a RDTI 62 asillustrated in B of FIG. 14. Further, two adjacent photodiodes 65 in thesame color in the block are separated by a P-type impurity layer 81 suchas boron. For example, two upper right photodiodes 65 in the block of Bare separated by the impurity layer 81. The same applies to the blocksof G and R.

On the other hand, the block of 2×2 photodiodes 65 is, on a frontsurface side, basically separated by a FDTI 61 as illustrated in C ofFIG. 14. Moreover, a substantially center portion of the FDTI 61extending in the longitudinal direction as viewed in the figure isreplaced with the impurity layer 81. Further, the 2×2 photodiodes 65 inthe block are separated by the impurity layer 81.

As illustrated in A of FIG. 14 illustrating the configuration of thecross section along the A-A′ line of C of FIG. 14, the photodiodes 65 inthe same color are separated by the impurity layer 81. For example,separation by the impurity layer 81 is made at a boundary betweenphotodiodes 65 positioned at the center of a color filter 66R in thecolor of R in a right-to-left direction and a boundary betweenphotodiodes 65 positioned at the center of a color filter 66G in thecolor of Gin the right-to-left direction. Ata boundary between adjacentcolors, separation is made by the RDTI 62 on the back surface side (theupper side as viewed in the figure), and separation is made by the FDTI61 on the front surface side (the lower side as viewed in the figure).

In the example of FIG. 14, it is configured such that pixels in the samecolor are not separated by the RDTI 62, but it can be configured suchthat these pixels are separated by the RDTI 62. Moreover, the FDTI 61 isnot formed between the pixels in the same color in a case where an OFSwith a charge tunneling structure is used between the pixels in the samecolor on the front surface side, and can be formed in the case of usingthe OFS.

FIG. 15 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. Thesolid-state imaging element 51 illustrated in FIG. 14 can have a backsurface configuration as illustrated in FIG. 15 instead of theconfiguration illustrated in B of FIG. 14. As clearly seen fromcomparison between FIG. 15 and B of FIG. 14, a configuration example ofFIG. 15 is made such that an intersection portion between adjacentportions of the RDTI 62 and an intersection portion between the RDTI 62and the impurity layer 81 are separated by the P-type impurity layer 81.Other configurations are similar to those in the case illustrated in Bof FIG. 14.

(6) Configuration 3 of Still Another Combination of FDTI and RDTI

FIG. 16 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. B and C ofFIG. 16 respectively illustrate the configurations of the back and frontsurfaces of the solid-state imaging element 51, and A of FIG. 16illustrates a configuration of a cross section of the solid-stateimaging element 51 along an A-A′ line of C of FIG. 16.

FIG. 16 illustrates an example in a case where photodiodes 65 areconfigured in two tiers. As illustrated in B of FIG. 16, 2×2 photodiodes65 on a back surface side form a block, and each block is separated by aRDTI 62. The 2×2 photodiodes 65 in each block are separated by animpurity layer 81.

A front surface side is similarly configured as in the example of C ofFIG. 12. That is, as illustrated in C of FIG. 16, 2×2 photodiodes 65 onthe front surface side forma single block, and the periphery thereof isseparated by a FDTI 61.

Of the 2×2 photodiodes 65 in each block, adjacent photodiodes 65 in aright-to-left direction in C of FIG. 16 are separated by the P-typeimpurity layer 81. Moreover, of the 2×2 photodiodes 65 in each block,right and left end portions of adjacent photodiodes 65 in anupper-to-lower direction in C of FIG. 16 are separated by the FDTI 61,and the remaining center portions of these photodiodes 65 are separatedby the impurity layer 81.

Thus, as illustrated in A of FIG. 16, the configuration of the crosssection along the A-A′ line of C of FIG. 16 is, on the front surfaceside (the lower side as viewed in the figure), made such that the FDTI61 and the impurity layer 81 alternately separate lower photodiodes 65arranged in the right-to-left direction. On the back surface side (theupper side as viewed in the figure), the RDTI 62 and the impurity layer81 alternately separate upper photodiodes 65 arranged in theright-to-left direction.

For charge transfer of the photodiodes 65 in two tiers, a verticaltransistor structure can be used, or a transfer plug can be formed of animpurity by ion implantation.

FIG. 17 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. Thesolid-state imaging element 51 illustrated in FIG. 16 can have a backsurface configuration as illustrated in FIG. 17 instead of theconfiguration illustrated in B of FIG. 16. As clearly seen fromcomparison between FIG. 17 and B of FIG. 16, a configuration example ofFIG. 17 is made such that an intersection portion between adjacentportions of the RDTI 62 and an intersection portion between the RDTI 62and the impurity layer 81 are separated by the P-type impurity layer 81.Other configurations are similar to those in the case illustrated in Bof FIG. 16.

(7) Configuration 4 of Still Another Combination of FDTI and RDTI

FIG. 18 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. B and C ofFIG. 18 respectively illustrate the configurations of the back and frontsurfaces of the solid-state imaging element 51, and A of FIG. 18illustrates a configuration of a cross section of the solid-stateimaging element 51 along an A-A′ line of C of FIG. 18.

On a back surface side, 2×2 photodiodes 65 form a block, and each blockis separated by a FDTI 61 as illustrated in B of FIG. 18. The 2×2photodiodes 65 in each block are separated by a RDTI 62.

On a front surface side, 2×2 photodiodes 65 forma single block, and theperiphery thereof is separated by the FDTI 61 as illustrated in C ofFIG. 18.

In each block, adjacent photo diodes 65 in a right-to-left direction areseparated by a P-type impurity layer 81, and adjacent photodiodes 65 inan upper-to-lower direction are separated by the P-type impurity layer81.

Thus, as illustrated in A of FIG. 18, the FDTI 61 and the impurity layer81 alternately separate, in the cross section along the A-A′ line of Cof FIG. 18, the photodiodes 65 arranged in the right-to-left direction.

FIG. 19 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. Thesolid-state imaging element 51 illustrated in FIG. 18 can have a backsurface configuration as illustrated in FIG. 19 instead of theconfiguration illustrated in B of FIG. 18. As clearly seen fromcomparison between FIG. 19 and B of FIG. 18, a configuration example ofFIG. 19 is made such that an intersection portion between adjacentportions of the RDTI 62 in each block are separated by the P-typeimpurity layer 81. Other configurations are similar to those in the caseillustrated in B of FIG. 18.

(8) Configuration 5 of Still Another Combination of FDTI and RDTI

FIG. 20 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. B and C ofFIG. 20 respectively illustrate the configurations of the back and frontsurfaces of the solid-state imaging element 51, and A of FIG. 20illustrates a configuration of a cross section of the solid-stateimaging element 51 along an A-A′ line of C of FIG. 20.

In the solid-state imaging element 51 of the embodiment of FIG. 20, 2×2photodiodes 65 on a back surface side form a single block, and the blockis separated by a FDTI 61 at right and left boundaries and by a RDTI 62at upper and lower boundaries as illustrated in B of FIG. 20.

In the block, the vicinity of right and left end portions at a boundarybetween upper and lower sides for separating the photodiodes 65 to theupper and lower sides are separated by the FDTI 61, and the vicinity ofthe center of the block at a boundary between right and left sides forseparating the photodiodes 65 to the right and left sides is separatedby the FDTI 61. Eventually, three side surfaces of the photodiode 65 areseparated by the FDTI 61, and the remaining one side surface of thephotodiode 65 is separated by the RDTI 62.

On a front surface side, 2×2 photodiodes 65 forms a single block, andthe block is separated by the FDTI 61 at right and left boundaries andby an impurity layer 81 at upper and lower boundaries as illustrated inC of FIG. 20.

In the block, the vicinity of upper and lower end portions at a boundarybetween the right and left sides of C of FIG. 20 is separated by theFDTI 61, and the vicinity of right and left end portions at a boundarybetween the upper and lower sides of C of FIG. 20 is also separated bythe FDTI 61. In the vicinity of the center of the block, separation bythe impurity layer 81 is made at both of the boundary between the upperand lower sides and the boundary between the right and left sides.

As illustrated in A of FIG. 20, the photodiodes 65 are separated by theFDTI 61 in the cross section along the A-A′ line of C of FIG. 20.

FIG. 21 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. Thesolid-state imaging element 51 illustrated in FIG. 20 can have a backsurface configuration as illustrated in FIG. 21 instead of theconfiguration illustrated in B of FIG. 20. As clearly seen fromcomparison between FIG. 21 and B of FIG. 20, a configuration example ofFIG. 21 is made such that center portions of the 2×2 photodiodes 65 ineach block are separated to the upper, lower, right, and left sides bythe RDTI 62. That is, the FDTI 61 and the RDTI 62 are, for the same sidesurface of the photodiode 65, arranged next to each other in a direction(a transverse direction) perpendicular to the optical axis of a lens 67.Moreover, two side surfaces of the photodiode 65 are separated by theFDTI 61 and the RDTI 62, and the remaining two side surfaces of thephotodiode 65 are separated by the FDTI 61 or the RDTI 62. Otherconfigurations are similar to those in the case illustrated in B of FIG.20.

(9) Configuration 6 of Still Another Combination of FDTI and RDTI

FIG. 22 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. B and C ofFIG. 22 respectively illustrate the configurations of the back and frontsurfaces of the solid-state imaging element 51, and A of FIG. 22illustrates a configuration of a cross section of the solid-stateimaging element 51 along an A-A′ line of C of FIG. 22.

In the solid-state imaging element 51 of the embodiment of FIG. 22, 2×2photodiodes 65 on a back surface side form a single block, and the blockis separated by a FDTI 61 at right and left boundaries and by a RDTI 62at upper and lower boundaries as illustrated in B of FIG. 22.

In the block, separation by the RDTI 62 is made at a boundary betweenupper and lower sides and a boundary between right and left sides.Eventually, three side surfaces of the photodiode 65 are separated bythe RDTI 62, and the remaining one side surface of the photodiode 65 isseparated by the FDTI 61.

On a front surface side, 2×2 photodiodes 65 forms a single block, andthe block is separated by the FDTI 61 at right and left boundaries asillustrated in C of FIG. 22. The block is separated by an impurity layer81 at upper and lower boundaries.

In the block, separation by the impurity layer 81 is made at a boundarybetween the upper and lower sides and a boundary between the right andleft sides. Eventually, three side surfaces of the photodiode 65 areseparated by the impurity layer 81, and the remaining one side surfaceof the photodiode 65 is separated by the FDTI 61.

As illustrated in A of FIG. 22, a right or left end of each of fourphotodiodes 65 is separated by the FDTI 61 in the cross section alongthe A-A′ line of C of FIG. 22. Moreover, two left photodiodes areseparated from two right photodiodes by the FDTI 61. The two leftphotodiodes 65 are separated by the RDTI 62 and the impurity layer 81,and the two right photodiodes 65 are separated by the RDTI 62 and theimpurity layer 81.

FIG. 23 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. Thesolid-state imaging element 51 illustrated in FIG. 22 can have a backsurface configuration as illustrated in FIG. 23 instead of theconfiguration illustrated in B of FIG. 22. As clearly seen fromcomparison between FIG. 23 and B of FIG. 22, a configuration example ofFIG. 23 is made such that an intersection portion between the RDTI 62for separating the 2×2 photodiodes 65 to the upper and lower sides andthe RDTI 62 for separating the 2×2 photodiodes 65 to the right and leftsides is separated by the impurity layer 81. Other configurations aresimilar to those in the case illustrated in B of FIG. 22.

(10) Configuration 7 of Still Another Combination of FDTI and RDTI

FIG. 24 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. B and C ofFIG. 24 respectively illustrate the configurations of the back and frontsurfaces of the solid-state imaging element 51, and A of FIG. 24illustrates a configuration of a cross section of the solid-stateimaging element 51 along an A-A′ line of C of FIG. 24.

In the solid-state imaging element 51 of the embodiment of FIG. 24, 2×2photodiodes 65 on a back surface side form a single block, and eachblock is separated by a FDTI 61 at a boundary surrounding such a blockas illustrated in B of FIG. 24. Moreover, in each block, right and leftend portions at a boundary for separating the 2×2 photodiodes 65 toupper and lower sides and upper and lower end portions at a boundary forseparating the 2×2 photodiodes 65 to right and left sides are separatedby the FDTI 61. Further, center portions of the 2×2 photodiodes 65 areseparated by a RDTI 62 at the boundary between the upper and lower sidesand the boundary between the right and left sides. That is, two sidesurfaces of the photodiode 65 are separated by the FDTI 61 and the RDTI62, and the remaining two side surfaces of the photodiode 65 areseparated by the FDTI 61. The FDTI 61 and the RDTI 62 are arranged nextto each other in a direction (a transverse direction) perpendicular tothe optical axis of a lens 67 to face the same side surface of thephotodiode 65.

On a front surface side, 2×2 photodiodes 65 also form a single block,and each block is also separated by the FDTI 61 at a boundarysurrounding such a block as illustrated in C of FIG. 24. Moreover, ineach block, right and left end portions at a boundary for separating the2×2 photodiodes 65 to the upper and lower sides and upper and lower endportions at a boundary for separating the 2×2 photodiodes 65 to theright and left sides are separated by the FDTI 61. Further, the vicinityof the center of each block is separated by the impurity layer 81 at theboundary between the upper and lower sides and the boundary between theright and left sides.

As illustrated in A of FIG. 24, four photodiodes 65 are separated by theFDTI 61 in the cross section along the A-A′ line of C of FIG. 24.

FIG. 25 is a view of the configuration of the solid-state imagingelement of the first embodiment of the present technology. Thesolid-state imaging element 51 illustrated in FIG. 24 can have a backsurface configuration as illustrated in FIG. 25 instead of theconfiguration illustrated in B of FIG. 24. As clearly seen fromcomparison between FIG. 25 and B of FIG. 24, a configuration example ofFIG. 25 is made such that an intersection portion between the RDTI 62for separating the 2×2 photodiodes 65 to the upper and lower sides andthe RDTI 62 for separating the 2×2 photodiodes 65 to the right and leftsides in the vicinity of the center is formed of the impurity layer 81.Other configurations are similar to those in the case illustrated in Bof FIG. 24.

Each side of the photodiode 65 can be separated by the FDTI 61 or theRDTI 62 alone or by a combination thereof. For the pixel transistor 73and the FD 71 susceptible to area restriction, the FDTI 61 and the RDTI62 can be used differently. Thus, the area of the photodiode 65 can beensured, color mixture can be reduced, and the saturated charge amountQs can be improved.

As described above, according to the present technology, at least one ormore sides of the photodiode 65 are separated by the FDTI 61 or the RDTI62. Thus, reliable light shielding can be realized, and color mixturecan be reduced. Even for a pixel with a great silicon film thickness,alight shielding effect can be improved. A portion separated by the FDTI61 and the RDTI 62 is selected so that the area of the photodiode 65 canbe ensured.

Moreover, the N-type impurity layer 63 and the P-type impurity layer 64are formed in the FDTI 61 by solid-phase diffusion, and therefore, theintense electric field portion can be formed on the surface of the FDTI61. Thus, the saturated charge amount Qs can be improved.

Note that in description above, the impurity layer 63 formed of theN-type impurity and the impurity layer 64 formed of the P-type impurityare formed by solid-phase diffusion, but can be formed by other methods.For example, these layers can be formed by tilt ion implantation, plasmadoping, epitaxial growth, vapor-phase diffusion, etc.

SECOND EMBODIMENT

(FDTI)

(1) Configuration of FDTI (FIG. 26, FIG. 27, FIG. 28)

FIG. 26 and FIG. 27 are views of a configuration of a solid-stateimaging element of a second embodiment of the present technology. Thesefigures illustrate a configuration of an individual imaging element 51.B of FIG. 26 illustrates a configuration of a cross section along anA-A′ line of A of FIG. 26. A of FIG. 27 illustrates a partialconfiguration (a single pixel 3) of A of FIG. 26, and B of FIG. 27illustrates a configuration of a cross section along an A-A′ line of Aof FIG. 27. Note that although not shown in these figures, the lenses 67illustrated in, e.g., A of FIG. 2 and B of FIG. 7 are arranged on thelower side as viewed in B of FIG. 26 and B of FIG. 27.

In the second embodiment, the FDTI 61 of the FDTI 61 and the RDTI 62 ofthe first embodiment will be mainly described. That is, in the secondembodiment, the solid-state imaging element 51 is also configured suchthat a wiring layer 162 is disposed on a first surface side (a frontsurface side) of a semiconductor layer 163 and an optical layer 164 isdisposed on a second surface side (a back surface side) facing a firstsurface as illustrated in B of FIG. 7. Moreover, a configuration of theFDTI 61 formed in the semiconductor layer 163 will be described.

Note that in the second embodiment, the wiring layer 162, thesemiconductor layer 163, and the optical layer 164 are not specificallyshown in the figures, but these terms will be used as necessary.

A of FIG. 26 illustrates a partial configuration (3×3 pixels 3) of thepixel region 4 of FIG. 1. As illustrated in A of FIG. 26 and A of FIG.27, a photodiode 311 (corresponding to the photodiode 65 of the firstembodiment) is disposed at the substantially center of the pixel 3 onthe front surface side. Moreover, a transfer gate 313 (corresponding tothe TG 72 of the first embodiment) and an N-type floating diffusion 314(corresponding to the FD 71 of the first embodiment) are arranged in thevicinity (the upper side as viewed in A of FIG. 27) of the photodiode311.

On the lower side of the photodiode 311 as viewed in A of FIG. 27, a STI323 (corresponding to the STI 191 of the first embodiment), a pixeltransistor 315 (corresponding to 73 of the first embodiment), and gatepolysilicon 316 are arranged.

A trench 312 (corresponding to the trench 111 of the first embodiment)is continuously formed at the entirety of the lower side of thephotodiode 311, part of the left side of the photodiode 311, and part ofthe right side of the photodiode 311 as viewed in A of FIG. 27. Thetrench 312 is a trench for a FDTI 310 (corresponding to the FDTI 61 ofthe first embodiment).

As viewed in the cross-sectional configuration illustrated in B of FIG.27, the trench 312 is formed on the left side of the N-type photodiode311. Moreover, an N-type impurity layer 321 (corresponding to theimpurity layer 63 of the first embodiment) is formed at the periphery ofthe trench 312, and a P-type impurity layer 332 (corresponding to theimpurity layer 64 of the first embodiment) is further formed inside (aside close to the trench 312) the impurity layer 321. As described inthe first embodiment, these layers are formed by solid-phase diffusion.The N-type impurity layer 321 is connected to the N-type photodiode 311.A P-type well 335 is formed below the N-type photodiode 311.

FIG. 28 is a graph for describing characteristics of the solid-stateimaging element of the second embodiment of the present technology. A ofFIG. 28 shows an impurity concentration profile in a cross section(i.e., a PN joint portion) along a B-B′ line of B of FIG. 27, thevertical axis representing a concentration and the horizontal axisrepresenting a depth on the B-B′ line (at a position in the transversedirection as viewed in B of FIG. 27). A peak P-type impurityconcentration shown by a curve 351 is, e.g., 1e18/cm3 (a value within arange of 1e17 to 1e19/cm3). A peak N-type impurity concentration at thePN joint portion as shown by a curve 352 is, e.g., 1e17/cm3 (a valuewithin a range of 1e16 to 1e18/cm3). The depth (the depth at anintersection between the curve 351 and the curve 352) at the PN jointis, e.g., 60 nm (a value within a range of 2 to 150 nm).

According to solid-phase diffusion, a steep profile can be produced at aside surface of the trench 312 as a diffusion source. Thus, a steep PNjoint can be formed. As a result, an N-type impurity concentrationincreases, leading to an intense electric field. Thus, a saturatedcharge amount Qs can be increased. B of FIG. 28 shows electric fielddistribution at the PN joint portion, the vertical axis representing anelectric field and the horizontal axis representing the depth on theB-B′ line. A curve 361 shows an electric field intensity on the B-B′line, and shows that the electric field reaches its peak at a depth of60 nm. The electric field can be intensified, and therefore, the depthcan be shallower (in the present embodiment, the depth can be 60 nm).Thus, the photodiode 311 can be expanded.

A thermally-oxidized film (a silicon oxide film) 324 with 5 nm (a valuewithin a range of 2 to 20 nm) is, for example, formed at a Si interfaceof the trench 312, and an embedded film (a silicon oxide film) 325formed by CVD is embedded in the trench 312. A region 327 on theopposite side of the trench 312 from the transfer gate 313 is of anN-type when the N-type impurity layer 321 is formed by solid-phasediffusion. Thus, this region 327 becomes a P-type by additional ionimplantation of a P-type impurity (e.g., boron).

In such a structure, the PN joint is close to the interface of thetrench 312, and therefore, there is a probability that the Si interfaceof the trench 312 is susceptible to influence of a depletion layerelectric field of the PN joint portion. That is, an end portion of adepletion layer formed between the N-type impurity layer 321 and theP-type impurity layer 332 in the vicinity of the Si interface comes intocontact with the Si interface, and therefore, a weak electric field isapplied to the Si interface. However, the Si interface of the trench 312is the thermally-oxidized film 324, and therefore, an interface state isreduced. Dark current and white spots can be suppressed to such a levelthat no problem is caused in imaging characteristics. As describedabove, the depth of the PN joint can be shallowed to about 60 nm, and awide area of the photodiode 311 can be obtained. Thus, the saturatedcharge amount Qs can be increased.

(2) Method for Manufacturing FDTI (FIG. 29, FIG. 30, FIG. 31)

Next, the method for manufacturing the individual imaging element 51will be described with reference to FIG. 29 and FIG. 30. FIG. 29 is aflowchart for describing the method for manufacturing the solid-stateimaging element of the second embodiment of the present technology, andFIG. 30 is a view for describing the method for manufacturing thesolid-state imaging element of the second embodiment of the presenttechnology.

First, the processing of forming a trench 312 is executed at a stepS101. That is, e.g., a silicon substrate 401 (corresponding to thesubstrate 101 of FIG. 4 of the first embodiment) is prepared, and asilicon nitride film 411 for masking is formed on a surface of thesubstrate 401. Then, the trench 312 is, using the silicon nitride film411 as a mask, formed from a front surface side by lithography andetching (A of FIG. 30).

As in the case of B of FIG. 4 of the first embodiment, a front surfaceside (i.e., a side on which a wiring layer 162 is to be disposed) of asemiconductor layer 163 is in an upward direction in A of FIG. 30. Thatis, the trench 312 is formed from the front surface side (the side onwhich the wiring layer 162 is to be disposed) of the semiconductor layer163.

At a step S102, the processing of forming an N-type impurity layer 321at the periphery of the trench 312 by solid-phase diffusion is executed.That is, e.g., a phosphorus-doped silicon oxide film 421 doped withphosphorus (P) as an N-type impurity is formed, and the N-type impuritylayer 321 is formed at the periphery of the trench 312 by heat treatment(B of FIG. 30). Thereafter, the phosphorus-doped silicon oxide film 421is removed. Then, by heat treatment, a broad phosphorus profile in asilicon substrate 401 is provided.

At a step S103, the processing of forming a P-type impurity layer 332 atthe periphery of the trench 312 by solid-phase diffusion is executed.That is, e.g., a boron-doped silicon oxide film 431 doped with boron (B)as a P-type impurity is formed, and the P-type impurity layer 332 isformed at the periphery of the trench 312 by heat treatment (C of FIG.30). Thereafter, the boron-doped silicon oxide film 431 is removed.

At a step S104, the processing of performing thermal oxidation of a sidewall of the trench 312 is executed. That is, e.g., a thermally-oxidizedfilm (a silicon oxide film) 324 with a thickness of 5 nm is formed onthe side wall of the trench 312 by thermal oxidation. Further, anembedded film (a silicon oxide film) 325 is embedded in the trench 312by a CVD method (D of FIG. 30). In this manner, a FDTI 310 is formed.

At a step S105, the processing of forming an N-type/P-type region of aphotodiode 311 is executed. That is, ion implantation of an N-typeimpurity into the photodiode 311 is performed. Further, a region 327 onthe opposite side of the trench 312 from a transfer gate 313 becomes aP-type by ion implantation of a P-type impurity.

That is, when the N-type impurity 321 is formed by solid-phasediffusion, the type of region 327 which becomes an N-type by doping iscanceled by ion implantation of the P-type impurity, and becomes theP-type. Moreover, according to a normal manufacturing method, a gateelectrode is formed.

Note that the above-described manufacturing steps of FIG. 30 can bethose illustrated in FIG. 31. FIG. 31 is a view for describing themethod for manufacturing the solid-state imaging element of the secondembodiment of the present technology.

That is, after the step of A of FIG. 30, the phosphorus-doped siliconoxide film 421 is formed at the step of B of FIG. 30. Then, before heattreatment, the phosphorus-doped silicon oxide film 421 can beselectively removed. That is, as illustrated in A of FIG. 31, a portionof the phosphorus-doped silicon oxide film 421 on the opposite side (theleft side as viewed in A of FIG. 31) of the transfer gate 313 in thetrench 312 is selectively removed by lithography and etching.

Thereafter, the N-type impurity layer 321 is formed only on an innerside wall portion of the trench 312 close to the transfer gate 313 (theright side as viewed in A of FIG. 31) by solid-phase diffusion by heattreatment (A of FIG. 31). Then, as described with reference to C of FIG.30, the boron-doped silicon oxide film 431 is formed in the trench 312,and solid-phase diffusion is performed by heat treatment to form theP-type impurity layer 332 (B of FIG. 31).

Further, the thermally-oxidized film (the silicon oxide film) 324 isformed on the side wall of the trench 312 by thermal oxidation of theside wall of the trench 312. Then, the embedded film (the silicon oxidefilm) 325 is embedded in the trench 312 by the CVD method (C of FIG.31).

In this case, the portion of the phosphorus-doped silicon oxide film 421on the opposite side (the left side as viewed in A of FIG. 31) of thetransfer gate 313 in the trench 312 is selectively removed, andtherefore, the N-type impurity layer 321 is not formed in the region 327on the opposite side (i.e., a side close to a STI 323) of the trench 312from the transfer gate 313 (B of FIG. 31). That is, only the P-typeimpurity layer 332 is formed, and therefore, the step of converting, byion implantation of the P-type impurity, the region 327 on the oppositeside of the trench 312 from the transfer gate 313 back into the P-typeas performed at the step S105 of FIG. 29 can be omitted.

(3) Another Configuration 1 of FDTI (FIG. 32)

FIG. 32 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. In a pixel 3of a solid-state imaging element 51 of FIG. 32, an embedded film 431embedded in a trench 312 is formed of polysilicon or silicon nitridewith a doped impurity amount of equal to or less than 1e16/cm3. Otherconfigurations are similar to those in the case of B of FIG. 27. Thepolysilicon or the silicon nitride exhibits better embeddingcharacteristics than those of a silicon oxide film. Thus, such amaterial exhibits similar electric characteristics, but exhibitsimproved embedding characteristics as compared to the case of B of FIG.27.

(4) Still Another Configuration 2 of FDTI (FIG. 33)

FIG. 33 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. In a pixel 3of FIG. 33, an embedded film 441 embedded in a trench 312 is formed ofpolysilicon or metal with a doped phosphorus impurity amount of equal toor greater than 1e16/cm3 and equal to or less than 1e23/cm3, forexample. Then, e.g., a voltage of −1.2 V is applied to the embedded film441 from a contact 442.

By negative potential application to the polysilicon, holes areconcentrated on an interface of the trench 312 of a silicon substrate.Electrons generated at the interface of the trench 312 are introducedinto the holes before flowing into a photodiode 311. This reducesoccurrence of dark current and white spots.

(5) Still Another Configuration 3 of FDTI (FIG. 34)

FIG. 34 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. In a pixel 3of FIG. 34, a fixed charge film 451 with a negative fixed charge isformed on a thermally-oxidized film 324 in a trench 312. Thereafter, asilicon oxide film is embedded as an embedded film 325 in the trench312.

Because of the presence of the fixed charge film 451 with the negativefixed charge, holes are concentrated on an interface of the trench 312of a silicon substrate, and electrons generated at the interface of thetrench 312 are introduced into the holes before flowing into aphotodiode 311. This reduces occurrence of dark current and while spots.

The fixed charge film 451 with the negative fixed charge is, forexample, formed of a hafnium oxide (HfO₂) film, an aluminum oxide(Al₂O₃) film, a zirconium oxide (ZrO₂) film, a tantalum oxide (Ta₂O₅)film, or a titanium oxide (TiO₂) film. The above-described types offilms have a track record in use for a gate insulating film etc. of aninsulating gate type field-effect transistor, and therefore, a filmformation method has been established. Thus, these types of films can beeasily formed. For example, a chemical vapor deposition method, asputtering method, anatomic layer deposition method, etc. can be used asthe film formation method.

Moreover, e.g., lanthanum oxide (La₂O₃), praseodymium oxide (Pr₂O₃),cerium oxide (CeO₂), neodymium oxide (Nd₂O₃), promethium oxide (Pm₂O₃),samarium oxide (Sm₂O₃), europium oxide (Eu₂O₃), gadolinium oxide(Gd₂O₃), terbium oxide (Tb₂O₃), dysprosium oxide (Dy₂O₃), holmium oxide(HO₂O₃), erbium oxide (Er₂O₃), thulium oxide (Tm₂O₃), ytterbium oxide(Yb₂O₃), lutetium oxide (Lu₂O₃), and yttrium oxide (Y₂O₃) can be used asother materials than above.

Further, the fixed charge film 451 with the negative fixed charge can beformed of a hafnium nitride film, an aluminum nitride film, a hafniumoxynitride film, or an aluminum oxynitride film. For these films, thechemical vapor deposition method, the sputtering method, the atomiclayer deposition method, etc. can be also used, for example. However,the atomic layer deposition method can be preferably used because a SiO₂layer for reducing an interface state during film formation can besimultaneously formed to about 1 nm.

(6) Still Another Configuration 4 of FDTI (FIG. 35)

FIG. 35 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. In a pixel 3of FIG. 35, a cavity 455 is formed in a trench 312. That is, in thisexample, no embedded film is present. Thus, the number of steps isreduced by the absence of the embedded film, leading to an efficientmanufacturing step.

(7) Still Another Configuration 5 of FDTI (FIG. 36)

FIG. 36 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. In a pixel 3of FIG. 36, a trench 312 (therefore, a FDTI 310) is formed in such acomb-tooth shape that the trench 312 not only extends at the outerperiphery of a photodiode 311, but also continuously extends from theouter periphery into the photodiode 311 to bite into the photodiode 311in a line shape.

In this case, the surface area of the trench 312 (therefore, thephotodiode 311) is increased, and therefore, a saturated charge amountQs can be increased.

(8) Still Another Configuration 6 of FDTI (FIG. 37)

FIG. 37 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. In a pixel 3of FIG. 37, a trench 312 (therefore, a FDTI 310) is not only formed atthe outer periphery of a photodiode 311, but also is formednon-continuously with the outer periphery in an island shape in thephotodiode 311.

In this case, the surface area of the trench 312 is also increased, andtherefore, a saturated charge amount Qs can be increased.

(9) Still Another Configuration 7 of FDTI (FIG. 38)

FIG. 38 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. In a pixel 3of FIG. 38, a P-type layer 326 is also formed on a surface of aphotodiode 311 by solid-phase diffusion. That is, as clearly seen fromcomparison between A of FIG. 38 and C of FIG. 30, when a boron-dopedsilicon oxide film 431 is formed for solid-phase diffusion of a P-typeimpurity layer 332, a silicon nitride film 411 for masking is not formedat a portion of a trench 312 on the right side as viewed in the figure(A of FIG. 38). As a result, when solid-phase diffusion of the P-typeimpurity layer 332 into a silicon substrate 401 from the trench 312 isperformed by heat treatment, solid-phase diffusion is also performed forthe surface of the photodiode 311 from the boron-doped silicon oxidefilm 431, and the P-type layer 326 is formed (B of FIG. 38).

In this case, as compared to a case where the P-type layer 326 on thesurface of the N-type photodiode 311 is formed by ion implantation, nodamage due to ion implantation is caused at the surface of the N-typephotodiode 311, and therefore, worsening of dark current and white spotsis reduced.

(10) Still Another Configuration 8 of FDTI (FIG. 39)

FIG. 39 is a view of the configuration of the solid-state imagingelement of the second embodiment of the present technology. B of FIG. 39illustrates a configuration of a cross section along an A-A′ line of Aof FIG. 39. As viewed in B of FIG. 39, a P-type well 501 is formed abovean N-type photodiode 311 on the right side of a left trench 312, and aP-type well 502 is formed above the N-type photodiode 311 on the leftside of a right trench 312. Moreover, in a pixel 3 of FIG. 39, thetrench 312 (therefore, a FDTI 310) is formed surrounding the peripheryof the pixel 3 as illustrated in

A of FIG. 39. That is, a pixel transistor 315 is disposed in the pixel3, and the trench 312 is formed between adjacent pixels 3.

In this case, the surface area of the trench 312 is also increased, andtherefore, a saturated charge amount Qs can be increased.

(11) Another Method for Manufacturing FDTI (FIG. 40, FIG. 41)

Next, another method for manufacturing the FDTI 310 will be described.FIG. 40 is a flowchart for describing the method for manufacturing thesolid-state imaging element of the second embodiment of the presenttechnology, and FIG. 41 is a view for describing the method formanufacturing the solid-state imaging element of the second embodimentof the present technology.

First, the processing of forming a trench 312 is executed at a stepS201. That is, a silicon substrate 401 is prepared, and a siliconnitride film 411 for masking is formed on a surface of the siliconsubstrate 401. Then, the trench 312 is formed using the silicon nitridefilm 411 as a mask by lithography and etching (A of FIG. 41).

At a step S202, the processing of forming an N-type impurity layer 601at the periphery of the trench 312 by tilt ion implantation is executed.That is, tilt ion implantation of phosphorus (P) into the trench 312 isperformed, for example. Thereafter, a broad phosphorus profile in thesilicon substrate 401 is provided by heat treatment (B of FIG. 41).

At a step S203, the processing of forming a P-type impurity layer 611 atthe periphery of the trench 312 by tilt ion implantation is executed.That is, tilt ion implantation of boron (B) into the trench 312 isperformed, for example. In this manner, the P-type impurity layer 611 isformed on the N-type impurity layer 601 (C of FIG. 41).

At a step S204, the processing of performing thermal oxidation of a sidewall of the trench 312 is executed. That is, e.g., a thermally-oxidizedfilm (a silicon oxide film) 324 with a thickness of 5 nm is formed onthe side wall of the trench 312 by thermal oxidation. Further, anembedded film (a silicon oxide film) 325 is embedded in the trench 312by a CVD method (D of FIG. 41). In this manner, a FDTI 310 is formed.

At a step S205, the processing of forming an N-type/P-type region of aphotodiode 311 is executed. That is, ion implantation of an N-typeimpurity into the photodiode 311 is performed. Further, a region 327 onthe opposite side of the trench 312 from a transfer gate 313 becomes aP-type by ion implantation of a P-type impurity.

That is, when the N-type impurity 321 is formed by solid-phasediffusion, the type of region 327 which becomes an N-type by doping iscanceled by ion implantation of the P-type impurity, and becomes theP-type. Moreover, according to a normal manufacturing method, a gateelectrode is formed.

Alternatively, the N-type impurity layer 601 and the P-type impuritylayer 611 can be, in addition to tilt ion implantation, formed by plasmadoping, epitaxial growth, vapor-phase diffusion, etc.

THIRD EMBODIMENT

(Electronic Apparatus Using Solid-State Imaging Element) (FIG. 42)

The solid-state imaging element of the present technology as describedin the embodiments above is applicable to an electronic apparatusincluding, for example, camera systems such as a digital camera and avideo camera, mobile phones having an imaging function, and other typesof equipment having an imaging function. This electronic apparatus willbe described below with reference to FIG. 42.

FIG. 42 is a diagram for describing a configuration of the electronicapparatus of a third embodiment of the present technology. FIG. 42illustrates, as an example of the electronic apparatus of the presenttechnology, a configuration diagram of a camera using a solid-stateimaging element. The camera of the present embodiment is an examplevideo camera configured to acquire a still image or a video. This camera700 has a solid-state imaging element 1, an optical system 701configured to guide incident light to a light receiving sensor of thesolid-state imaging element 1, a shutter device 702, a drive circuit 703configured to drive the solid-state imaging element 1, and a signalprocessing circuit 704 configured to process an output signal of thesolid-state imaging element 1.

The configuration described in each embodiment above is employed for thesolid-state imaging element 1. The optical system 701 forms, from imagelight from an object, an image on an imaging area of the solid-stateimaging element 1. In this manner, a signal charge is accumulated in thesolid-state imaging element 1 for a certain period of time. Such anoptical system 701 may be an optical lens system including a pluralityof optical lenses.

The shutter device 702 controls the period of light irradiation and theperiod of light shielding for the solid-state imaging element 1. Thedrive circuit 703 supplies the solid-state imaging element 1 and theshutter device 702 with a drive signal, thereby controlling, accordingto the supplied drive signal such as a timing signal, signal outputoperation from the solid-state imaging element 1 to the signalprocessing circuit 704 or shutter operation of the shutter device 702.That is, the drive circuit 703 transfers the signal from the solid-stateimaging element 1 to the signal processing circuit 704 by a drive signalsupply.

The signal processing circuit 704 performs various types of signalprocessing for the signal transferred from the solid-state imagingelement 1. The video signal subjected to the signal processing is storedin a storage medium such as a memory, or is output and displayed on amonitor.

According to the electronic apparatus of the present embodimentdescribed above, any of the solid-state imaging elements described inthe embodiments above and exhibiting favorable light receivingcharacteristics is used so that high-definition imaging and sizereduction can be realized.

Note that the embodiments of the present technology are not limited tothe above-described embodiments, and various changes can be made withoutdeparting from the gist of the present technology.

OTHER

The present technology can employ the following configurations.

(1)

A solid-state imaging element including:

a photoelectric converter configured to perform photoelectric conversionof incident light;

a first separator configured to separate the photoelectric converter andformed in a first trench formed from a first surface side; and

a second separator configured to separate the photoelectric converterand formed in a second trench formed from a second surface side facing afirst surface.

(2)

The solid-state imaging element according to (1), in which

in the first trench, a first impurity layer formed of an N-type impurityand a second impurity layer formed of a P-type impurity are formed bysolid-phase diffusion.

(3)

The solid-state imaging element according to (1) or (2), in which

the first separator and the second separator are arranged next to eachother in a direction parallel to an optical axis of a lens through whichlight enters the photoelectric converter.

(4)

The solid-state imaging element according to (1), (2) or (3) in which

the photoelectric converter includes photoelectric converters in twotiers, the photoelectric converter on the first surface side beingseparated by the first separator and the photoelectric converter on thesecond surface side being separated by the second separator.

(5)

The solid-state imaging element according to any of (1) to (4), in which

a periphery of a block including 2×2 photoelectric converters isseparated by the first separator.

(6)

The solid-state imaging element according to any of (1) to (5), in which

the first separator and the second separator are arranged next to eachother in a direction perpendicular to an optical axis of a lens throughwhich light enters the photoelectric converter.

(7)

The solid-state imaging element according to any of (1) to (6), in which

in the first trench, a first impurity layer formed of an N-typeimpurity, a second impurity layer formed of a P-type impurity, and athermally-oxidized film are formed.

(8)

The solid-state imaging element according to any of (1) to (7), in which

a wiring layer is disposed on the first surface side of a semiconductorlayer having the photoelectric converter, the first separator, and thesecond separator, and an optical layer is disposed on the second surfaceside.

(9)

A method for manufacturing a solid-state imaging element, including:

a step of forming a first trench from a first surface side;

a step of forming, in the first trench, a first separator for separatinga photoelectric converter;

a step of forming a second trench from a second surface side facing afirst surface; and

a step of forming, in the second trench, a second separator forseparating the photoelectric converter.

(10)

An electronic apparatus including:

a solid-state imaging element configured to acquire an image of anobject; and

a signal processor configured to process an image signal output from thesolid-state imaging element,

in which the solid-state imaging element includes

-   -   a photoelectric converter configured to perform photoelectric        conversion of incident light,    -   a first separator configured to separate the photoelectric        converter and formed in a first trench formed from a first        surface side, and    -   a second separator configured to separate the photoelectric        converter and formed in a second trench formed from a second        surface side facing a first surface.        (11)

A solid-state imaging element including:

a photoelectric converter configured to perform photoelectric conversionof incident light; and

a separator configured to separate the photoelectric converter,

in which the separator includes

-   -   N-type and P-type impurity layers formed in a trench for        separating the photoelectric converter, and    -   a thermally-oxidized film formed on the impurity layers.        (12)

The solid-state imaging element according to (11), in which the impuritylayers are formed by solid-phase diffusion.

(13)

The solid-state imaging element according to (11) or (12), in which

the N-type impurity layer is formed only on a transfer gate side in thetrench, and is not formed on an opposite side of the transfer gate.

(14)

The solid-state imaging element according to (11), (12) or (13), inwhich

an embedded film to which a predetermined voltage is to be applied isembedded in the trench.

(15)

The solid-state imaging element according to any of (11) to (14), inwhich

a fixed charge film with a negative fixed charge is formed on thethermally-oxidized film.

(16)

The solid-state imaging element according to any of (11) to (15), inwhich

the separator is formed surrounding a periphery of a pixel.

(17)

The solid-state imaging element according to any of (11) to (16), inwhich

the trench is formed from a first surface side of a semiconductor layerhaving the photoelectric converter and the separator, a wiring layerbeing disposed on the first surface side, and

an optical layer is disposed on a second surface side facing a firstsurface.

(18)

The solid-state imaging element according to any of (11) to (17), inwhich

the impurity layers are formed by tilt ion implantation, plasma doping,epitaxial growth, or vapor-phase diffusion.

REFERENCE SIGNS LIST

-   1 Individual imaging element-   3 Pixel-   51 Individual imaging element-   61 FDTI-   32 RDTI-   63 N-type impurity layer-   64 P-type impurity layer-   65 Photodiode-   67 Lens-   310 FDTI-   311 Photodiode-   312 Trench-   321 N-type impurity layer-   332 P-type impurity layer-   324 Thermally-oxidized film-   325 Embedded film

What is claimed is:
 1. A solid-state imaging element comprising: aphotoelectric converter configured to perform photoelectric conversionof incident light; a first separator configured to separate thephotoelectric converter and formed in a first trench formed from a firstsurface side; and a second separator configured to separate thephotoelectric converter and formed in a second trench formed from asecond surface side facing a first surface.
 2. The solid-state imagingelement according to claim 1, wherein in the first trench, a firstimpurity layer formed of an N-type impurity and a second impurity layerformed of a P-type impurity are formed by solid-phase diffusion.
 3. Thesolid-state imaging element according to claim 2, wherein the firstseparator and the second separator are arranged next to each other in adirection parallel to an optical axis of a lens through which lightenters the photoelectric converter.
 4. The solid-state imaging elementaccording to claim 2, wherein the photoelectric converter includesphotoelectric converters in two tiers, the photoelectric converter onthe first surface side being separated by the first separator and thephotoelectric converter on the second surface side being separated bythe second separator.
 5. The solid-state imaging element according toclaim 2, wherein a periphery of a block including 2×2 photoelectricconverters is separated by the first separator.
 6. The solid-stateimaging element according to claim 2, wherein the first separator andthe second separator are arranged next to each other in a directionperpendicular to an optical axis of a lens through which light entersthe photoelectric converter.
 7. The solid-state imaging elementaccording to claim 1, wherein in the first trench, a first impuritylayer formed of an N-type impurity, a second impurity layer formed of aP-type impurity, and a thermally-oxidized film are formed.
 8. Thesolid-state imaging element according to claim 2, wherein a wiring layeris disposed on the first surface side of a semiconductor layer havingthe photoelectric converter, the first separator, and the secondseparator, and an optical layer is disposed on the second surface side.9. A method for manufacturing a solid-state imaging element, comprising:a step of forming a first trench from a first surface side; a step offorming, in the first trench, a first separator for separating aphotoelectric converter; a step of forming a second trench from a secondsurface side facing a first surface; and a step of forming, in thesecond trench, a second separator for separating the photoelectricconverter.
 10. An electronic apparatus comprising: a solid-state imagingelement configured to acquire an image of an object; and a signalprocessor configured to process an image signal output from thesolid-state imaging element, wherein the solid-state imaging elementincludes a photoelectric converter configured to perform photoelectricconversion of incident light, a first separator configured to separatethe photoelectric converter and formed in a first trench formed from afirst surface side, and a second separator configured to separate thephotoelectric converter and formed in a second trench formed from asecond surface side facing a first surface.
 11. A solid-state imagingelement comprising: a photoelectric converter configured to performphotoelectric conversion of incident light; and a separator configuredto separate the photoelectric converter, wherein the separator includesN-type and P-type impurity layers formed in a trench for separating thephotoelectric converter, and a thermally-oxidized film formed on theimpurity layers.
 12. The solid-state imaging element according to claim11, wherein the impurity layers are formed by solid-phase diffusion. 13.The solid-state imaging element according to claim 11, wherein theN-type impurity layer is formed only on a transfer gate side in thetrench, and is not formed on an opposite side of the transfer gate. 14.The solid-state imaging element according to claim 11, wherein anembedded film to which a predetermined voltage is to be applied isembedded in the trench.
 15. The solid-state imaging element according toclaim 11, wherein a fixed charge film with a negative fixed charge isformed on the thermally-oxidized film.
 16. The solid-state imagingelement according to claim 11, wherein the separator is formedsurrounding a periphery of a pixel.
 17. The solid-state imaging elementaccording to claim 11, wherein the trench is formed from a first surfaceside of a semiconductor layer having the photoelectric converter and theseparator, a wiring layer being disposed on the first surface side, andan optical layer is disposed on a second surface side facing a firstsurface.
 18. The solid-state imaging element according to claim 11,wherein the impurity layers are formed by tilt ion implantation, plasmadoping, epitaxial growth, or vapor-phase diffusion.